GCSE Sciences
TEACHER GUIDE
Version 1
August 2014
GCSE SCIENCES
TEACHER GUIDE
CONTENTS
INTRODUCTION3
EXEMPLAR MATERIALS
5
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TEACHER GUIDE
INTRODUCTION
The key aims of this document are to help teachers understand
how a mark scheme is applied to exam questions, with
particular focus on level of response questions. By improving
the understanding of how a mark scheme is applied, teachers
can better prepare candidates for the style of questions they will
face in the examinations.
used to assess student understanding in the same way that
student progress might be assessed during a lesson through
‘hinge’ questions.
Tick boxes/circling correct answers
These can range from recall of facts from the specification to
application of knowledge questions. The more challenging
style of question can ask students to read information, make
decisions about the information and apply their knowledge in a
variety of ways.
This document aims to;
• Highlight areas where candidates can be better trained in the
process of completing exam questions
• Offer advice to teachers on how simple mistakes can be
avoided to gain the maximum score for closed response and
level of response style questions
Common errors in this style of question include;
• Identifying the wrong number of responses needed –
ticking more boxes than is required shows uncertainty in
the response and so will lose marks. This might also include
ticking too few boxes eg where 2 ticks are needed for 1 mark
• Provide an insight into the marking of level of response style
questions including commentaries on how the mark scheme
has been applied by examiners
• Identifying statements that are factually correct statements
but they don’t answer the question that has been posed.
Such statements are deliberate distractors used to
differentiate the knowledge the student has as well as how
well they apply their knowledge in that particular situation
• Allow the opportunity for teacher to test themselves on the
marking of level of response style questions.
Command words
Candidates should experience training in the vocabulary
used in an examination. This will help students to approach
the questions that are set in a more confident manner. By
understanding the command words the examiner uses, the
candidate is ensuring they do what they have been asked to do
to be awarded marks. For example describe and explain are two
very different command words.
• Changing the answer. Whilst examiners make every effort
to award marks for correct science, this is sometimes made
difficult by the changing of responses. If students want
to change a response they need to make it clear to the
examiner which answer they would like marking. eg crossing
out of ticks needs to be done in such a way that it is clear
which tick is their final response. This also applies to circling
of answers and joining of boxes using lines.
Describe – the candidate will be required to say what they see
from a graph/diagram/experiment/table etc.
Connecting boxes
Explain – The candidate will be required to make a link
between statements/say why a phenomenon occurs/say how
phenomenon are linked etc. These style of questions need more
than just a simple statement to be made and are often 2 or
more marks.
There is a temptation for students to connect boxes up even
when they are not required to do so. Students need to read the
instructions carefully to decide how many boxes need to be
connected. As with tick box style questions, students will lose
marks for drawing too many lines to connect boxes or too many
lines leaving, or joining a single box as this again shows doubt in
the students understanding.
Compare – To answer this style of question correctly often
needs an ‘er’ word such as greater, higher, lower, longer, shorter,
slower, faster, further, closer, brighter, dimmer, bigger, smaller,
quieter, noisier, etc. These are a good starting point to begin
constructing responses. There are obvious exceptions that do
not work here such as more and less reactive.
Calculations
Students should always be encouraged to show their workings
for all calculations they are asked to carry out. Where more than
one mark is awarded for the calculation it is possible to gain
credit for the correct working.
Closed response questions
These are often perceived as the ‘easy’ tick box style questions.
This is simply not the case. Whilst there is a small chance that
candidates can ‘guess’ the correct answer, multiple choice
questions are very carefully constructed and can be effectively
Students often press the wrong buttons on their calculator
when carrying out calculations. When the working is shown
but the wrong buttons pressed then credit can be given for the
correct process rather than just the expected numerical value.
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TEACHER GUIDE
Where calculation questions follow on from each other but the
student does not know how to answer the first part but feels
able to answer the second part, they should use any value of
their choice as a response to the first part to enable them to
gain ‘error carried forward’ marks for the second process in the
sequence.
Level of response style questions (6 marks)
These questions are marked very differently to other questions
on an exam paper. In this case the response is read as a whole
and the ideas within it are assessed against a 3 level structure.
A response which meets the criteria set out by the command
words and has clear science content will score a level 3. A ‘level
2’ response will have some science content and may not address
all aspects of the command words in the question. These
questions are not marked using a tick system. The quality of
written communication is also judged in this style of question.
When reading the mark scheme for such questions it is
important to remember that the left hand side gives you the
expected actions for the command words and what are the
expected ideas needed to achieve a particular level, whereas
the right hand side contains statements that are indicative
science content. The list is not a complete list and credit may
be awarded for a response that includes statements not in the
indicative science content section.
It should be noted that writing more does not score more marks
and that the quality of the answer is judged rather than the
number of points made. If an essential point is missed then the
response may be deemed to be a lower level.
Examples of where levels are not achieved might include;
• Giving only advantages when both disadvantages are also
required from the command words (or vice versa)
• Only describing instead of explaining a phenomenon when
an explanation is required from the command words
• Making unrelated statements rather than linking ideas
together in a response.
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Exemplar materials
This section contains actual examples of student responses from previous series of examinations and the judgements made by lead/
senior examiners in the form of commentaries.
A171-01 January 2013 (Chemistry based question)
Level 1 response
Describe and explain the advantages and disadvantages of adding chlorine to water supplies.
The quality of written communication will be assessed in your answer.
The advantages of adding chlorine to water is it kills off any germs and bacteria found in the water and also helps to
keep teeth white. A disadvantage to this is it can be exspensive and also if the right amount of chlorine isn’t added it
can make people ill and can kill.
[6]
This response gives only advantages of adding chlorine. There is enough indicative content for 2 marks. ‘Kills off bacteria’ is well
expressed (2 marks) but ‘gets rid of bacteria’ would be limited by QWC (1 mark) as this is not clear what is happening to the bacteria.
Level 2 response
Describe and explain the advantages and disadvantages of adding chlorine to water supplies.
The quality of written communication will be assessed in your answer.
An advantage of adding chlorine to water supplies is that through the chlorination process, the chlorine kills bacteria
in the water, this can stop the disease cholera spreading. A disadvantage is that the chlorine can react with other
chemicals in the water to make toxins. This is poisonous to us and can have harmful effects.
[6]
This response gives reasonable detail when discussing the advantages of adding chlorine. The candidate has also attempted to
discuss disadvantages but ‘other chemicals in the water’ is not enough to gain credit, although ‘make toxins’ implies the product of
such a reaction would be toxic. This is clearly expressed and so 4 marks are awarded. There is not enough detail or explanation given
for the disadvantages of adding chlorine for this to be a level 3 response.
Level 3 response
Describe and explain the advantages and disadvantages of adding chlorine to water supplies.
The quality of written communication will be assessed in your answer.
The Advatages of using chlorine in water is that it kills all disease-causing micro-organisms, prevents fungi from
developing, gets rid of nasty smells and prevents the water from developing a colour, however chlorine has
disadvantages like causing organic compounds in the water to turn into chlorinated hydrocarbons which is carcingenic
(cancer-causing), also breathing chlorine in can irritate lungs, this can happen when taking shower and steam is
breathed in, and chlorine as liquid can seriously irritate the eyes.
[6]
This response has clearly described and explained the advantages and disadvantages of adding chlorine to water. It contains all
aspects required from a level 3 response. This scores 6 marks.
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A171-01 January 2013 – Mark scheme
A171/01
Mark Scheme
January 2013
Question
Answer
Marks
Guidance
6
Level 3 (5–6 marks)
Answer gives full details of both advantage
and disadvantage.
Quality of written communication does not
impede communication of the science at this
level.
6
This question is targeted at grades up to E
(a)
Indicative scientific points may include:
Advantages;
• chlorine kills bacteria
• bacteria can cause disease
• disease can be spread in water supply
• example of water-borne disease eg cholera
Level 2 (3–4 marks)
Answer gives some details of both advantage
and disadvantage, or one in full detail.
Quality of written communication partially
impedes communication of the science at this
level.
Disadvantages;
• chlorine reacts with organic materials in water
• product is toxic/carcinogen
• products of this reaction can affect health
Ignore taste/colour/smell of water
Level 1 (1–2 marks)
Answer relates only to advantage or
disadvantage in limited detail, not both.
Quality of written communication impedes
communication of the science at this level.
Use the L1, L2, L3 annotations in Scoris: do not use
ticks
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
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A153-02 June 2013 (Physics based question)
Level 1 response
Explain how food is sterilised by radiation. Include safety aspects.
The quality of written communication will be assessed in your answer.
The food is exposed to beta (β) particles, which destroy the bacteria from the food, both inside and out? One of the
safety issues with using radiation to sterilise food is that the food may now contain radioactive particles, which could
contaminate someone if the product is ingested.
[6]
This response scores only 1 mark. They have given an explanation of a procedure. ‘Destroy the bacteria’ is just equivalent to kill
bacteria. This is a very basic response as it gives no mention of the actual procedure – eg using gamma rays/radiation. It does not
give any safety aspects either. In this case ‘beta’ is ignored.
Level 2 response
Explain how food is sterilised by radiation. Include safety aspects.
The quality of written communication will be assessed in your answer.
The food is sterilised when it is exposed to a large amount of radiation, it goes through a scanner which kills off all the
microbes from the food meaning it is fresher and doesn’t have to be frozen. People who work in a processing centre
place the fruit on the scanner wearing protective clothing, they also come out of the room before exposing a large
amount of radiation. They wear protective gloves to ensure that they are not contaminated, just irradiated.
[6]
This response has an explanation and a safety aspect but no procedure. They have not said that gamma rays are used but they
have explained that it kills off all the microbes. A safety feature of protective clothing has been given. This is a level 2 response but is
weakened as it has not given a procedure. It scores 3 marks.
Level 3 response
Explain how food is sterilised by radiation. Include safety aspects.
The quality of written communication will be assessed in your answer.
When food is sterilised by radiation, gamma rays are fired at the food. These rays kill all the microbes in the food,
allowing it to be fresher for longer. Gamma rays are only stopped by very thick lead or other thick metals, which means
they will penetrate through the food and not stay in it, causing damage to the people who eat it. This is all done in a
secure machine, so it will not harm the people working at the processing centre.
[6]
This response has identified the procedure of using gamma rays. It has explained this by describing the killing of microbes and the
penetration through the food. It has a safety aspect of using a ‘secure machine’ but this is weak. This is a level 3 response but scores
only 5 marks due to the poor safety description. A better description of safety would have given 6 marks.
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A153/02 June 2013 – Mark scheme
A153/02
Mark Scheme
Question
Answer
Marks
Guidance
1
Level 3 (5–6 marks)
Identifies procedures linked to correct
explanation AND safety aspect
Quality of written communication does not
impede communication of the science at this
level.
6
This question is targeted at grades up to B
June 2013
Indicative Science points may include:
Procedure & explanation
• use ionising radiation (gamma/X-Ray) – Idea that
radiation is able to penetrate fruit and packaging
• use ionising radiation (gamma/X-Ray) – ionising
radiation kills microorganisms
• wrap food in airtight material – prevent
microorganisms getting in after sterilisation
• leave close to radioactive material – to give
microorganisms a high dose
• long exposure time – to give microorganisms a high
dose.
Level 2 (3–4 marks)
Identifies procedures
OR
Identifies a procedure with linked to correct
explanation
OR
Identifies a procedure and safety aspect.
Quality of written communication partly
impedes communication of the science at this
level.
Ignore references to alpha and beta
Ignore get rid of/remove bacteria
Safety Aspects
• shielding/protective clothing
• workers don’t go near source
• workers wear monitoring badges/check ups
• workers exposure to radiation is limited to permitted
levels.
Ignore safety goggles/masks
Ignore safety aspects linked to consumers
Level 1 (1–2 marks)
Identifies a procedure OR safety aspect.
Quality of written communication impedes
communication of the science at this level.
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
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A153/02 June 2013 (Biology based question)
Level 1 response
Describe the features and mechanisms in the brain that allow it to adapt so that Jenny can learn to speak
again.
The quality of written communication will be assessed in your answer.
Jenny is able to learn to speak again by listening to her surrondings. The repitition of words would create lines in her
brain and as she hears the words over again the lines begin to thicken enabling her to be able to speak again.
[6]
This response has the idea of repetition only. The rest of the response has no credit worthy science. This scores 2 marks as the idea is
clearly expressed.
Level 2 response
Describe the features and mechanisms in the brain that allow it to adapt so that Jenny can learn to speak
again.
The quality of written communication will be assessed in your answer.
For Jenny to be able to speak again she will have to strengthen her pathways again. And for this to happen people will
need to always speak around her as repetition will also make new pathways to help her be able to speak. Another thing
she can do is develop a conditioned reflex.
[6]
This a level 2 response as the candidate has given an incomplete description of 2 mechanisms rather than identifying a feature and
a mechanism. This is a best fit model so it is awarded level 2. The idea of new pathways and repetition are clear, but the idea that the
pathways are strengthened by repetition is not explicit. This scores 3 marks.
Level 3 response
Describe the features and mechanisms in the brain that allow it to adapt so that Jenny can learn to speak
again.
The quality of written communication will be assessed in your answer.
There are billions of possible neuron pathways that could be taken. In order for Jenny to learn to speak again she will
have to transmit impulses along new pathways in the cerebral cortex that control her speech. By continually practising
with her speech therapist she is strengthening those pathways, this makes them easier to follow and therefore speak.
The part of the cerebral cortex that controls memory is also a key factor. By using the action of storage and retrieval she
won’t forget how she learned to speak previously.
[6]
This response has a very clear description of features and mechanisms. They have identified the large number of neurones in the
brain and that the cerebral cortex is responsible for speech. The mechanisms have been clearly stated as new pathways are formed
and that these are strengthened through repetition. This scores 6 marks.
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A153/02 June 2013 – Mark scheme
A153/02
Mark Scheme
Question
Answer
8
Level 3 (5–6 marks)
6
Identification of some features and detailed
description of mechanisms to include neurons.
Quality of written communication does not
impede communication of the science at this
level.
(a)
Marks
Level 2 (3–4 marks)
Identification of a feature and an incomplete
description of a mechanism.
Quality of written communication partially
impedes communication of the science at this
level.
June 2013
Guidance
This question is targeted at grades up to A*
Relevant points include:
Mechanisms:
• learning involves new neuron pathways forming
• repetition will strengthen new pathways
• repetition means new pathways are more likely to
transmit
• damaged area bypassed
• brain neurons do not regenerate
Features:
• cerebral cortex identified as part of the brain affected
by stroke
• cerebral cortex is part of brain concerned with
language/communication/speech
• neurons in brain
• billions of neurons gives capacity to learn
• large number of neurons gives capacity to learn
Level 1 (1–2 marks)
Identifies a feature OR a statement about the
mechanism.
Quality of written communication impedes
communication of the science at this level.
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
ignore reference to the damaged site repairing
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A152-02 June 13 (Additional Science A based question)
Level 1 response
Here is a generator of alternating current. Explain the shape of the graph. You may add labels to the diagram.
The quality of written communication will be assessed in your answer.
The graph shows the current and the time starting at 0. Also magnet spins near some coiled wires These show how it
can all change.
[6]
This candidate has mentioned that the magnet must rotate near the coil (so could be level 2), but there is no overt causal link
between current and changes of the magnet, so fits better with level 1. So one mark.
Level 2 response
Here is a generator of alternating current. Explain the shape of the graph. You may add labels to the diagram.
The quality of written communication will be assessed in your answer.
As the magnet does a half-turn the current increases then decreases. When the other side of the magnet is near the coil
the current on the scale heads down and then back up once the magnet has completed it’s half-turn.
[6]
Candidate has identified the magnet and the coil and has attempted to explain the current in terms of the rotation of the magnet –
so level 2. However, there is no mention of changing poles, magnetic field etc – only three marks.
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Level 3 response
Here is a generator of alternating current. Explain the shape of the graph. You may add labels to the diagram.
The quality of written communication will be assessed in your answer.
The shape of the graph represents the rotating movement the magnet is doing. At the first high peak in current on
the graph it shows the south side of the magnet has rotated past the coil. This will increase the current (shown on the
graph). At the lowest peak it shows that the magnet is now vertical meaning neither the north or south side of the
magnet is close to the coil. This will decrease the current which is represented by the dip in current on the graph. The
next high peak shows that the north side of the magnet is now next to the coil which will increase the current shown
on the graph.
[6]
The candidate correctly explains the alternating nature of the current in terms of the changing poles of the magnet at the end of
the coil. The rotation of the magnet is mentioned as well, so best fit is to level 3. (Explanations in terms of changing poles are as
acceptable as those in terms of changing magnetism or magnetic field). However, the lack of identification of the core suggest a
mark of 5.
A152/02 June 2013 – Mark scheme
A152/02
Mark Scheme
Question
Answer
Marks
Guidance
4
Level 3 (5–6 marks)
The candidate identifies both properties
and explains them in terms of the structure/
bonding of graphite.
Quality of written communication does not
impede communication of the science at this
level.
6
This question is targeted at grades up to A.
June 2013
Relevant points include
electrical conductivity
• high conductivity/conductor of electricity
• because
(only) three bonds for each atom
(some) electrons free to move
Level 2 (3–4 marks)
Candidate identifies either of the properties
and explains it in terms of the structure/
bonding of graphite.
Quality of written communication partly
impedes communication of the science at this
level.
melting point
• high (above 800OC)
• because
giant structure
strong bonding
covalent bonds
difficult to separate/lot of energy needed
Level 1 (1–2 marks)
Candidate either identifies one of the
properties or describes the structure/bonding
of graphite.
Quality of written communication impedes
communication of the science at this level.
Use the L1, L2, L3 annotations in Scoris; do not use
ticks.
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
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A152-02 June 2013 (Additional Science A based question)
Level 0 response
Dutch elm disease has killed many elm trees in England. Some elms are resistant to the disease. Park keepers
want to plant resistant elm trees to replace one that have been killed. They decide to use cuttings from the
resistant elms, rather than using seeds. Describe the process of using cuttings, and explain why they choose
this method.
The quality of written communication will be assessed in your answer.
They use cutting as its easy. Also it will be the same as the original, it also will have the same as they they will have the
same nucleus. Also they will grow quicker too.
[6]
There is no description of how to grow cuttings, nor is there any science in the justification. They will have the same what? Number
of leaves, initials carved into their trunk, final height? No marks.
Level 1 response
Dutch elm disease has killed many elm trees in England. Some elms are resistant to the disease. Park keepers
want to plant resistant elm trees to replace one that have been killed. They decide to use cuttings from the
resistant elms, rather than using seeds. Describe the process of using cuttings, and explain why they choose
this method.
The quality of written communication will be assessed in your answer.
Cuttings are taken from the shoot of a tip as it contains unspecialised cells that divide mitotically. Cuttings are clones
and are identical to the parent cell and contain the same genes. Also unspecialised cells may develop into any type of
cell. Additionally, auxins are used to increase the production of it’s growth.
[6]
The candidate has provided a small bit of information about how to take cuttings, but this is more than just one omission from a
practical procedure, suggesting it is below level 2. The description is very brief indeed. They have said that cuttings are clones with
the same genes as the parent tree, so could be level 1. However, there is no mention of inherited resistance. So the justification is
incomplete, suggesting a mark of 1.
Level 2 response
Dutch elm disease has killed many elm trees in England. Some elms are resistant to the disease. Park keepers
want to plant resistant elm trees to replace one that have been killed. They decide to use cuttings from the
resistant elms, rather than using seeds. Describe the process of using cuttings, and explain why they choose
this method.
The quality of written communication will be assessed in your answer.
Chosing the method of cutting is better because you have to cut a bit of the stem and the side of the leaf then you
have to plant it in soil. It won’t grow if it only has water and light. Rooting powder needs to be adding (Plant hormones).
This helps it grow faster and exactly like the plant it was cloned from. This method save a lot of time and money.
[6]
This candidate has fully described a procedure which would work. Although the justification is very shallow (no mentions of genes
or inherited resistance), the best fit is level 2. So deserves four marks.
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Level 3 response
Dutch elm disease has killed many elm trees in England. Some elms are resistant to the disease. Park keepers
want to plant resistant elm trees to replace one that have been killed. They decide to use cuttings from the
resistant elms, rather than using seeds. Describe the process of using cuttings, and explain why they choose
this method.
The quality of written communication will be assessed in your answer.
A cutting is taken from the shoot of a plant so that it is a meristem, containing unspecialised cells to allow it to
grow. This cutting is planted in the ground usually with a rooting hormone to help roots grow to get water for
photosynthesis. The plant then grows into a clone of the original as is has the same DNA. This is good and better than
seeds because it means you can get a plant (tree) with the properties you want, in this case resistant to Dutch elm
disease, to help improve survival.
[6]
The described procedure would work in practice, so at least level 2. However the justification contains lots of good science and is
complete, so level 3. Six marks.
This question is also on the Foundation paper, so it is to be expected that the majority of our candidates will earn at least half marks,
and quite a few should get to level 3.
A152/02 June 2013 – Mark scheme
A152/02
Mark Scheme
Question
Answer
Marks
Guidance
11
Level 3 (5–6 marks)
Describes a cutting method which would
work. Either justifies use of cuttings or not use
of seeds. Quality of written communication
does not impede communication of the
science at this level.
6
This question is targeted at grades up to C
June 2013
Relevant points may include:
method
• cut off (small) shoot/branch
• dip in (hormone) powder
• place in soil/compost
• water regularly
• until roots develop/leaves grow
Level 2 (3–4 marks)
Describes a practical cutting method with a
significant error or omission. Either justifies
use of cuttings or not use of seeds. Could be
just a description of a cutting method which
would work. Quality of written communication
partially impedes communication of the
science at this level.
justification
• (mature) plants are clones with inherited resistance
• because they have same genes/DNA as parent tree
• seeds formed by meiosis/sexual reproduction
• not all seeds will have resistance
• as they have genes from two trees
Level 1 (1–2 marks)
Either brief description of cutting method
or justifies use of cuttings or justifies not use
of seeds. Quality of written communication
impedes communication of the science at this
level.
ignore argument based on the relative speed of each
method
ignore discussions about meristems, unspecialised cells ....
ignore argument based on cost
Use the L1, L2, L3 annotations in Scoris; do not use
ticks.
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
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A171-01 June 12 – To be used for exercise
Exercise
Before any examiner can start to mark an examination paper, they must firstly write their own responses to the questions. This helps
to get a feel for the requirements of the questions as well as give the examiner an insight to the possible responses a candidate
might give.
Write your own answers to the question provided below.
(b) Many scientists are worried about the rise in carbon dioxide in the air.
One cause of extra carbon dioxide is burning fuels.
Some people grow trees to burn as firewood.
Sue is talking about how growing and burning trees affects the levels of carbon dioxide in the air.
Sue
Growing and burning trees makes no difference to
the total amount of carbon dioxide in the air.
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................
................................................................................................................................................................................................................................................................[6]
Check your own answer against the mark scheme provided.
Now use the mark scheme provided to mark the responses below.
Actual marks and commentaries are provided.
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Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
When the trees grow, they produce their own food by photosynthsis, this takes in carbon dioxide and releases oxygen.
When the trees are burning they release carbon dioxide but use oxygen to burn, so I think that Sue is correct on her
statement.
[6]
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
I think Sue is incorrect. When burning wood it produces carbon dioxide which will cause the level in the air to rise.
When trees grow it causes oxygen. So when cutting down trees it is lowering the oxygen level.
[6]
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
Sue is wrong because when we have cut down the trees and burnt them harmful gases such as carbon dioxide
are made and are released into the atmosphere. This means that there will be more CO2. Also trees are needed for
photosynthesis. photosynthesis converts carbon dioxide into oxygen. If there are less trees they won’t be able to
photosynthesis.
[6]
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A171/01 June 2012 – Mark scheme
A171/01
Mark Scheme
Question
Answer
Marks
Guidance
1
Level 3 (5–6 marks)
Answer gives a full explanation of balance
between carbon dioxide absorption and
release and hence why Sue is correct. Quality
of written communication does not impede
communication of the science at this level.
6
This question is targeted at grades up to C
(b)
June 2012
Indicative scientific points may include:
• wood contains carbon compounds
• when wood burns carbon makes carbon dioxide
• when trees grow they take in carbon dioxide for
photosynthesis
• photosynthesis makes sugar/glucose/carbon
compounds
• trees use sugar/glucose to make other carbon
compounds
• trees also respire and produce carbon dioxide
• burning wood returns carbon dioxide to the air that
was removed from the air as the tree grew
• there is no net change of carbon dioxide in the air
(carbon neutral) so Sue is correct.
Level 2 (3–4 marks)
Answer gives some ideas of combustion
and photosynthesis. Candidate attempts
an explanation of the balance between
absorption and release of carbon dioxide.
Conclusion about Sue’s statement
may or may not be correct. Quality of
written communication partly impedes
communication of the science at this level.
Level 1 (1–2 marks)
Answer gives some ideas of combustion
or photosynthesis. Quality of written
communication impedes communication of
the science at this level.
Use the L1, L2, L3 annotations in Scoris; do not use
ticks.
Level 0 (0 marks)
Insufficient or irrelevant science. Answer not
worthy of credit.
17
GCSE SCIENCES
TEACHER GUIDE
Answers for exercise
Level 3 for 5 marks
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
When the trees grow, they produce their own food by photosynthsis, this takes in carbon dioxide and releases oxygen.
When the trees are burning they release carbon dioxide but use oxygen to burn, so I think that Sue is correct on her
statement.
[6]
This response has a good description of photosynthesis and a clear description of combustion. The candidate has identified that Sue
is correct but there is little discussion about the balance between the 2 processes so a mark of 5/6 has been awarded.
Level 1 for 2 marks
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
I think Sue is incorrect. When burning wood it produces carbon dioxide which will cause the level in the air to rise.
When trees grow it causes oxygen. So when cutting down trees it is lowering the oxygen level.
[6]
This response has a clear discussion of combustion and so scores 2 marks. The candidate has attempted to make a comment about
photosynthesis but there is not enough here to gain credit in the statement ‘when trees grow it causes oxygen’. A sensible comment
about photosynthesis would raise this response to level 2.
Q1b - Level 2 for 4 marks
Describe the processes that affect the amount of carbon dioxide in the air when wood burns and when trees
grow.
Explain whether you think Sue is correct or not.
The quality of written communication will be assessed in your answer.
Sue is wrong because when we have cut down the trees and burnt them harmful gases such as carbon dioxide
are made and are released into the atmosphere. This means that there will be more CO2. Also trees are needed for
photosynthesis. photosynthesis converts carbon dioxide into oxygen. If there are less trees they won’t be able to
photosynthesis
[6]
In this response the processes of combustion and photosynthesis have been discussed and are relatively clear. There is no discussion
of the balance in the processes and the decision has been made that ‘Sue is wrong’ and the lack of discussion limits this response to
level 2.
18
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